Multiple expansion-arbor



Patented Dec. 28, 1920.

2 SHEETSSHEET I.

W T CHRISTOPHER MULTIPLE EXPANSION ARBOR.

APPLICATION man NOV. 22. 1919.

W. T. CHRISTOPHER.

MULTIPLE EXPANSION ARBOR.

n I APPLICATION FILED NOV. 22.1919- lpfiSfilOu Patented Dec. 28, 1920.

2 s'nens-smasr 2.

N s Q: a

UNITED STATES PATENT OFFICE.

MULTIPLE EXPANSION-ARBOR.

Specification. of Letters Patent.

Patented Dec. 28, 1920.

Application filed November 22, 1919. Serial No. 339,844.

T 0 all whom it may concern:

Be it known that I, WALTER T. CHRISTO- II-IER, a citizen of the UnitedStates, residing at Detroit, in the county of Wayne and State ofMichigan, have invented certain new and useful Improvements in MultipleExpansion-Arbors, of which the following is a specification, referencebeing had to the accompanying drawings.

This invention relates to arbors or mandrels designed to be used betweencenters on machine tools such as lathes or the like, and particularly toan expanding arbor or mandrel.

The general object of my invention is to provide a very simple mandrelto be used between centers and upon which work to be turned or machinedis mounted, the mandrel consisting of a plurality of diametricallyexpansible sections, these sections being expanded by turning up thetail stock of the lathe or like machine.

A further object is to provide a mandrel of this character in which thearbor or mandrel is expanded at a plurality of points with even pressureat all points.

And a further object is to provide a con struction of this characterwherein there is a ball bearing center used in conjunction with themandrel at one end thereof whereby to take up the thrust and permit therotation of the mandrel against the action of the cutting tool.

A further object is to provide an arbor or mandrel which may be readilyremoved from the machine by simply releasing the tail stock at thecompletion of the travel of the cutting tool.

Other'objects will appear in the course of the following description.

My invention is illustrated in the accompanying drawings, wherein Figure1 is a longitudinal sectional view of an expanding. mandrel or arborconstructed in accordance with my invention, certain of the sectionsbeing shown in elevation;

Fig. 2 is a longitudinal sectional view of the. middle section A;

Fig. 3 is an end elevation thereof;

Fi 4 is a longitudinal section of the section Fig. 5 is an end elevationthereof;

Fig. 6 is a perspective view of the center section D;

Fig. 7 is a perspective view of the section B;

8 is a perspective view of the middle sect on A, Fig. 9 1s a perspectiveview of the section C;

Fig. 10 is a fragmentary perspective view of one of the centeringsections formed by the members E and F, the casing ring for the ballbearings being removed;

Referring to these drawings, it will be seen that my improved mandrel orarbor is made up of a plurality of sections. The middle section,disposed midway between the centers, is designated A and comprises acylindrical body 10 having conical bores 11 at its opposite ends, eachconical bore 11 terminating at its inner end in a longitudinal extension12 of uniform diameter. This section A at opposite ends islongitudinally slotted at a plurality of points, as at 13. This sectionin actual practice will be about 5 long and g" in diameter, though it isobvious that these measurements will vary. Engageable with the oppositeends of the section A are the sections B and C. Both these sections arealike and each section comprises a cylindrical body 14 having uniformdiameter and cut away at one end, as at 15, to form a shoulder and fromthis shoulder tapering uniformly in one direction, as at 16. Thisconical portion 16 fits into the corresponding conical socket 11 in thesection A. At its opposite end, each section B or C is formed with acentrally disposed, conical socket 17 and is longitudinally slotted, asat 18. These slots extend approximately the length of the correspondingsocket. The section B is formed at its outer end remote from thetapering portion 16 with an enlarged shoulder 19, the slots 18 extendingthrough this shoulder. This tapering socket 17 is preferably hexagonalor many-sided incross section on the section B, but the socket 17 onsection 0 is circular in cross section. Coact'ing with the section B isa center D which, at its middle portion, has a diameter slightly greaterthan the exterior diameter of the shoulder 19 and is formed on one sideof this middle portion 20 with a hexagonal, tapering portion 21 fittingwithin the socket 17 of the section B and on the opposite side of themiddle portion 20 with a conical portion 22 which is circular in crosssection. The portion 21 has a length somewhat greater than the hexagonalsocket 17. Its smallest diameter is the same as thediameter of thesmall-.

est portion of the socket 17, while its largest diameter is greater thanthe largest interior diameter of the socket 17, as illustrated clearlyin Fig. 1. The portion 22 which is formed with a Morse taper is designedto be engaged by the spindle of a lathe or like machine. 7

Designed to engage the socket in the sec tion C is a center section Ewhich is formed to provide a body of uniform diameter, designated 23, ashoulder 24 and tapering portion 25 having a length slightly greaterthan that of the socket 17 in section C, and this section E is formedwith a central bore 26. Coacting with this member E is a center memberor section F having a cylindrical body 27, on one face provided with thecentral gudgeon 28 and on its opposite face havin a tapered portion 29formed with a i. orse taper which is ada'pted'to be engaged by the tailstock of the lathe or like machine.

It will be seen that when the several sections as described are engagedwith each other, that pressure applied longitudinally will cause thoseportions of the members A, B and C which are slotted to be expanded andthat as the section A is slotted at oppo site ends and the sections Band C are each slotted at one end, the mandrel formed of these sectionsA, B and G will be expanded at four points. It will be likewise seenthat the hexagonal member 21 will cause the expansion of the section B,while the conical or tapering end 25 will cause the expansion of themember C. It will likewise be seen that the section D will cause therotation of the various sections B, A, C and E and that theanti-friction'balls 30 between the sections E and F will take up thethrust and allow the arbor or mandrel to rotate. Inasmuch as thecarrying center D has a hexagonal portion 21, this will allow the entirearbor to be removed from the machine by simply releasing the tail stockat the completion of the travel of the cutting tool.

In order to cause the sections B and C to rotate with the section A, thetapering portion 16 of these sections B and C are transverselyperforated, as at 31, and the opposite ends of the section A aretransversely perforated, as at 32, these perforations 32 being smallerthan the perforations or passages 31 so as to permit pins to be disposedthrough the sections A and B and the sections A and C, thusj oiningthesesections together for uniform rotative movement. The perforations31 are elliptical in cross section. The major diameter of the ellipse islonger than the diameter of the pins inserted through the perforations32, thus permitting a longitudinal movement of the sections B and Crelative to the section A.

It will be obvious that this expanding arbor or mandrel is very simplein construction, maybe easily applied and removed from the Work and fromthe machine with which it is designed to operate, and that it providesan expansion arbor which does not require to be operated by air pressureor hand labor. t will be obvious also that this arbor or mandrel may beused for engaging one or more objects simultaneously with an evenpressure. It will further be seen that the expansion of the mandrel orarbor takes place at a plurality of points and that this expansion isthe same at any point of expansion.

Furthermore, it will be noticed that the expansion is caused by shiftingthe tail stock inward and this action will not prevent the free rotationof the mandrel or arbor because of the friction balls 30 disposedbetween the members or sections E and F This arbor or mandrel can beremoved from the machine tool without the aid of small tools, andinasmuch as the carrying center D has a hexagonal portion, the entirearbor may be removed from the machine by simply releasing the tail stockat the completion of the travel of the cutting tool.

I claim 1. An expanding mandrel comprising a plurality of alinedsections, each section having a socket into which the other sectionfits, each socket being longitudinally split and the interfitting end ofthe other section being tapered to cause the expansion of said splitportions of the several sections upon the longitudinal movement of thesections toward the middle of the mandrel.

2. An expanding mandrel formed of a plurality of interfitting sectionscausing the expansion of the mandrel by movement toward the middle ofthe mandrel, and coacting members operatively engaging one end of themandrel and formed of two interfitting sections with anti-frictionelements disposed between the sections forming a thrust bearing.

3. An expanding mandrel including a middle section formed with taperingsockets at its ends, these tapering sockets being longitudinally splitand the sections at each end of the middle section and end sectionshaving tapering portions fitting in said sockets and adapted to expandthe latter upon longitudinal movement of said end sections toward eachother.

4. An expanding mandrel including a middle section formed with taperingsockets at its ends, these tapering sockets being longitudinally split.and the sections at each end of the middle section and end sectionshaving tapering portions fitting in said sockets and adapted to expandthe latter upon longitudinal movement of said end sections toward eachother, each end section having at its end opposite the tapering portiona tapering socket, the socket being longitudinally split at a pluralityof points, the tapering portions of said end sections and the socketportions of the middle section being formed with transversely extending,reg istering passages whereby the sections may be pinned to each other,the passages in the tapering portions of the end sections beinglongitudinally elongated.

5. An expanding mandrel including a middle section formed with taperingsockets at its ends, these tapering sockets being longitudinally splitand the sections at each end of the middle section and end sectionshaving tapering portions fitting in said sockets and adapted to expandthe latter upon longitudinal movement of said end sections toward eachother, each end section having at its end opposite the tapering portiona tapering socket, the socket being longitudinally split at a pluralityof points, the tapering portions of said end sections and the socketportions of the middle section being formed with transversely extending,registering passages whereby the sections may be pinned to each other,the passages in the tapering portions of the end sections beinglongitudinally elongated, centering sections having tapered portionsadapted to fit within the sockets of the end sections, one of saidcentering sections and the corresponding end section being many-sided incross section.

6. An expanding mandrel including a middle section formed with taperingsockets at its ends, these tapering sockets being longitudinally splitand the sections at each end of the middle section and end sectionshaving tapering portions fitting in said sockets and adapted to expandthe latter upon longitudinal movement of said end sections toward eachother, each end section having at its end opposite the tapering portiona tapering socket, the socket being longitudinally split at a pluralityof points, the tapering portions of said end sections and the socketportions of the middle section being formed with transversely extending,registering passages whereby the sections may be pinned to each other,the passages in the tapering portions of the end sections beinglongitudinally elongated, centering sections having tapered portionsadapted to fit within the sockets of the end sections, one of saidcentering sections and the corresponding end section being many-sided incross section, the opposite centering section being formed in two partsrotatably engaged with each other and having antifriction bearingsdisposed between the two parts.

7. In a mandrel expanded by longitudinal thrust, two coacting members,one of said members being tapering toward one end and formed with asocket in its other end, the other member being formed with a hub r0-tatably engaging in the socket and having a tapered portion extendingoppositely from said hub, and anti-friction bearings disposed betweenthe two members.

In testimony whereof I hereunto aflix my signature.

WALTER T. CHRISTOPHER.

